(1) Field of the Invention
The present invention relates to a package of a light-emitting semiconductor element. More particularly, the invention relates to a package of a light-emitting semiconductor element emitting light in two directions, such as a semiconductor laser.
(2) Description of the Prior Art
When light emitted in one direction from a light-emitting semiconductor element such as a semiconductor laser is applied to such use as optical-communication, a window is formed on a package and light from the light-emitting semiconductor element in the package is emitted to the outside and utilized through a lens system. On the other hand, light emitted from the other face is often used for monitoring the light output of this light-emitting semiconductor element. This light output is taken out through, for example, an optical fiber or glass rod, or it is directly applied to a light-receiving element to take out the output in the form of an electric signal.
FIG. 1 is a mode diagram illustrating the section of a conventional package of a light-emitting semiconductor element. In FIG. 1, reference numerals 1, 2, 3, 4, 5, 6 and 7 represent a stem, a light guide rod, a light take-out window, a light-emitting semiconductor element, reflected light, emitted light and a fixing member for the light guide rod, respectively. The structure in which the end face of a light guide confronts to the light-emitting face of a light-emitting semiconductor element as shown in FIG. 1 is illustrated in, for example, the specification of U.S. Pat. No. 4,097,891.
In such conventional structure, if a light guide such as a glass rod 2 is employed for monitoring, laser light is reflected on the end face of the glass rod and is emitted on the opposite side, that is, in the front direction of the cleave face. As a result, the light taken out from the front directly or through the window is overlapped on this reflected light to form an interference pattern.
The non-uniformity of the light output based on such interference pattern induces a noise when the system is used in optical-communication. Further, when such a conventional package is applied to another use, for example, when it is used as a light source for writing or reading by applying laser light to a recording layer, the above non-uniformity causes errors.
The present invention has been completed as a result of research made with a view to eliminating the foregoing defects involved in the conventional technique.